Know Thy Impact

John Hattie

Teachers give a lot of feedback, and not all of it is good. Here's how to ensure you're giving students powerful feedback they can
use.

Many years ago, I made a claim about the importance of giving students "dollops of feedback" (1999). This endorsement of giving great amounts of feedback
was based on the finding that feedback is among the most powerful influences on how people learn.

The evidence comes from many sources. My synthesis of more than 900 meta-analyses (2009, 2012) shows that feedback has one of the highest effects on student learning.
These meta-analyses focused on many different influences on learning—home, school, teacher, and curriculum—and were based on more than 50,000 individual
studies, comprising
more than 200 million students, from 4- to 20-year-olds, across all subjects. As an education researcher, I was seeking the underlying story about what separated those influences
that had a greater effect on student learning from those that had a below-average effect. Feedback was a common denominator in many of the top influences. Moreover, Dylan
Wiliam (2011) has argued that feedback can double the rate of learning, and an increasing number of scholars are researching this important notion (see Sutton, Hornsey, &
Douglas, 2012).